Rocker switch assembly



3, 1964 A. s. KLINGENBERG 3,155,806

ROCKER SWITCH ASSEMBLY Filed Oct. 26. 1961 //v VENTOR y AKL INGENBERG AT TORN United States Patent 3,155,866 RGCKER SW ASSEMBLY Alfred S.Klingenberg, Whippany, Ni, assignor to Bell Teiephene Laboratories,incorporated, New York, N.Y., a corporation of New York Filed Get. 26,rear, Ser. No. 147,989 1 iairn. ((35. lint- 167) This invention relatesto electrical switches, and more particularly to a switch assemblyembodying a pair of over-center electrical switches which areselectively actuated by a common actuator.

The typical over-center type electrical switch comprises a push buttonor plunger, spring means of some sort for resiliently urging the plungerto an outwardly extending position, and an over-center spring, sometimesformed integrally with the said spring means. The over-center spring isstable in either one of two positions (i.e., when the plunger is fullyextended or depressed), but unstable intermediate thereof. Thus, as theplunger is moved downward by the operator the condition of theover-center spring is changed from one of stability to one of increasinginstability, until at the intermediate position it snaps, at a very highspeed, to its other over-center stable condition. As pressure isreleased, the aforementioned spring means forces the plunger back to thenor mal extended position and the snap action of the overcenter springis thus repeated. The patents to G. M. Hausler, 2,332,911, issuedOctober 26, 1943; W. A. Martin, 2, 476,056, issued July 12, 1949; and A.P. Charbonneau, 2,526,850, issued October 24, 1950; and, for example,the commercially available V3 switches of Micro Switch, a division ofMinneapolis-Honeywell Regulator Company, exemplify the abovedescribedoperation.

Over-center type electrical switches are very popular. They are simple,compact and rugged in construction, fast and reliable in operation, andthey can be readily manufactured and assembled at low cost.

As exemplified by the cited patents, over-center type electricalswitches include spring means for resiliently urging, and therebyreturning, the plunger to the outwardly extended position. In theabsence of such a spring means, it would be necessary to grasp thedepressed button between the fingers and pull the same back to the saidextended position; or, alternatively, some form of manual return meanswould have to be provided. However, while the addition of such a springmeans readily solves the problem of plunger return, it prevents abistable type of operation. That is, the depressed condition of theplunger is retained only so long as the operator exerts physicalpressure on the same.

It is an object of the present invention to achieve an efficientbistable operation with snap-action over-center electrical switches.

A further object is to achieve a bistable rocker switch operation inelectrical switches without the use of holding devices such as holdingmagnets, spring loaded ball detents, offset cam surfaces, and the like.

A still further object is to simplify the means and mode of operation ofelectrical switches, whereby such switches may not only be economicallymanufactured, but will be more eflicient and satisfactory in use andadaptable to a wide variety of applications.

These and other objects are att ined in accordance with the presentinvention wherein a pair of over-center type electrical switches aremounted on a mounting frame in proximity to each other. A rocker (arm ispivotally mounted on said frame at a point equidistant between the pushbuttons of said electrical switches with the push buttons urged intoresilient contact engagement with opposite ends of said rocker arm. Therocker arm is capable of limited rotation in either direction about saidpivot whereby either one of the push buttons may be depressed. Thedepressed push button is then retained in this position by the resilientforce exerted against the opposite end of said rocker arm by the otherpush button. Since either button may be depressed and so retained, abistable switching arrangement is thereby achieved.

In accordance with a feature of the present invention, the contactengaging surfaces of said rocker arm can be effectively shifted withrespect to said push buttons to thereby achieve a make before break or abreak before make mode of switch operation.

In accordance with another feature, an additional spring means is addedto the switch assembly to normally bias the rocker arm in apredetermined direction. The actuation of the switch pair occurs asheretofore described, but the switch assembly is now monostable, i.e., apredetermined one of the pair of switches is normally in the actuated ordepressed condition.

In a further embodiment of the present invention the rocker armcomprises ends of transparent material integrally joined to anintermediate section of opaque material. A light is mounted adjacenteach of the ends of the rocker arm and an electrical energizing circuitfor the same is completed through the associated switch adjacent eachend. If a switch is in the make condition the associated light isenergized and the light from the same is diffused in the adjacent end ofthe rocker arm to thereby provide a visual indication of the state ofthe rocker switch assembly.

Other features and advantages of the invention will be readilyappreciated as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawing in which:

FIG. 1 is a side elevational view of a bistable rocker switch assemblyconstructed in accordance with the principles of the present invention;

FIG. 2 is a side elevational view, partly in section, of a monostablerocker switch assembly in accordance with the invention;

FIG. 3 is a perspective view of a plurality of rocker switch assembliesand visual indicating means therefor; and

FIG. 4 is a circuit diagram useful in the explanation of the operationof the FIG. 3 embodiment of the invention.

Referring now to FIG. 1 of the drawing, a pair of over-center typeelectrical switches 11 and 12 are attached to a mounting frame 13 byscrews or bolts 14 which extend through the switches and into the frame.The switches each include an operating plunger or push button 15 andconnecting terminals 16 which are adapted to be suitably connected toexternal electrical circuits. While the switches illustrated are of thesingle-pole doublethrow type, any other switch contact arrangement maybe utilized herein.

The switches 11 and 12 can comprises any of the various types ofover-center electrical switches known to those in the art. Typically,any of the above-cited patented switches can be advantageously utilizedherein.

A characteristic common to over-center type electrical switches, and onethat is utilized to advantage herein in accordance with the presentinvention, is the differential in the force exerted on the plunger bythe internal spring means of the switch. That is, the total outwardurging force that is exerted on the plunger is different for the twopositions of the latter. The said force exerted on the plunger in itsextended position exceeds that exerted in its depressed position. Thisforce differential results from the action of the over-center spring.With the plunger in its extended position, the over-center spring of theswitch coacts with the plunger return spring means in urging the plungerto said extended position. However, when the plunger is depressed andthe over-center spring is thereby snapped to the other over-centercondition, the spring force exerted by the latter opposes that of theplunger return spring means. The spring force of the plunger returnspring means must, of course, be the greater of the two so as to insureplunger return. This characteristic of over-center type switches isfamiliar to those skilled in the electrical switch art.

The over-center electrical switches 11 and 12 are disposed in proximityto each other on opposite sides of the pivot point 17 of rocker arm 18.The rocker arm is capable of limited rotational movement in eitherdirection about the pivot-point to thereby selectively depress either ofthe plungers 15. The rocker arm 18 is preferably formed of insulatingmaterial and it can be or" any given configuration.

The internal spring means of the over-center electrical switches 11 and12 urge the plungers of the latter into resilient contact engageemntwith opposite ends of the rocker arm 1%. Either of the electricalswitches can be actuated (i.e., the plunger can be depressed) byapplying pressure against the appropriate end of the rocker arm Ill Andthe depressed plunger is then retained in this condition by theresilient force exerted against the opposite end of said rocker arm bythe other plunger. The said other plunger, being extended, exerts agreater force against the rocker arm than the plunger that has beendepressed. Accordingly, since either plunger may be depressed and soretained, a bistable switching arrangement is thereby achieved.

The switches 11 and 12 are preferably aligned with each other andequidistant from the pivot point 17. Further, the point in the travel ofeach plunger at which the aforementioned over-center snap action occursshould cor-respond to that of the other. That is, the said points shouldpreferably lie in substantially the same horizontal plane. Now if, inthe intermediate position of said rocker arm, the contact engagingsurfaces 21 of said arm lie in substantially the same horizontal planeas that which includes the aforementioned points of snap action operation, the actuation of one switch will occur simultaneously with therelease of the other and vice versa. Hence, a simultaneous make andbreak mode of operation is thereby achieved.

Alternatively, if in the intermediate position of said rocker arm thecontact engaging surfaces 21 lie in a plane offset with respect to thatwhich includes the aforementioned points of snap action operation, theactuation of one switch and the release of the other will not occursimultaneously. Accordingly, a make before break or break before makemode of switch operation can thus be achieved. For example, in FIG. 1,if in the intermediate position of the rocker arm the surfaces 21 lie ina horizontal plane somewhat above that which includes the said points ofover-center snap action, both switches will be released for a finiteperiod. Thus, as the rocker arm is rocked from one position to theother, the depressed plunger will be released prior to the actuation ofthe other. Thus, depending upon the particular internal electricalswitch contact arrangement, a make before break or break before makemode of switch operation can be achieved.

The specific plane occupied by the contact engaging surfaces 21, for theaforementioned intermediate position of the rocker arm, can bedetermined most readily by appropriately locating the pivot point 17.

In the FIG. 2 embodiment of the invention, an addi tional spring meansis added to the switch assembly to normally bias the rocker arm in apredetermined direction. Thus, the switch assembly is made monostable,i.e., a predetermined one of the pair of switches is normally in theactuated or depressed condition. The additional spring means in thisinstance comprises a coil spring 25 which is disposed in a recess in oneend of the rocker arm 1%. The coil spring extends beyond the recess toresiliently engage the outer casing of the electrical switch ll.Accordingly, the rocker arm is biased in the illusstrated manner tothereby depress the plunger of switch 12. Pressure applied to therecessed end of the rocker arm will, of course, reverse the switchconditions, but as this pressure is subsequently released the switchassembly will revert to the normal illustrated state.

Turning now to FIG. 3 of the drawing, a plurality of switch assemblies,such as shown in ElG. 1, are mounted side by side within a casing 31formed preferably of insulating material, portions of said casing beingcut away for purposes of illustration. The mounting bolts or rods 14extend through the juxtaposed switches as shown. A thin sheet of opaquematerial 32 is disposed between each of the juxtaposed assemblies, andsmall light bulbs 33 are mounted on the same adjacent each of the endsof each rocker arm.

The rocker arms each comprise end portions formed of transparentinsulating material (e.g., methyl methacrylate) integrally joined to anintermediate section 19 of opaque insulating material. The end surfaces20' of the rocker arms are preferably glossed.

An electrical circuit, such as shown in FIG. 4, serves to energize agiven light bulb when the electrical switch adjacent the same end assaid bulb is switched to a predetermined (e.g., 1nalae) condition. Thus,for example, if the switch 12a of FIG. 3 is in its make condition partof the energizing current that is thereby delivered to external circuitsis coupled to the light bulb 33a via a current limiting resistor 49a.The light from the energized bulb passes into the adjacent end of theassociated rocker arm and is diflused therein to thus provide a visualindication of the position of the same. The opaque section 19, ofcourse, prevents passage of the light to the other end of this rockerarm.

A plurality of juxtaposed assemblies, such as shown in FIG. 3, can beutilized to manually set up a binary num her or word input to computermemories and the like. The binary number or word input will be visuallyindicated from a front panel by respective illuminated halves of eachrocker arm.

It is to be understood, therefore, that the abovedescribed embodimentsare merely illustrative of the principles and application of the presentinvention. Numerous other arrangements and modifications may be devisedby those skilled in the art without departing from the spirit and scopeof the invention.

What is claimed is:

A switch assembly comprising a casing of insulation material, aplurality of electrical switches within said casing juxtaposed in tworows with each switch having its match in the opposite row so as toconstitute a plurality of opposed switch pairs, each of said electricalswitches including a plunger and means for resiliently urging saidplunger to an outwardly extending position, said resilient meansincluding over-center spring means which adds to the outward urgingforce exerted on said plunger when the same is in its extended positionand subtracts from said force when the plunger is depressed whereby thesaid force exerted on said plunger in its extended position exceeds thatexerted in its depressed condition, sheets of opaque material disposedbetween said switch pairs so as to optically isolate each of said switchpairs from adjacent switch pairs, bolts extending through the juxtaposedswitches for the purpose of fixing the position of said switches andsaid sheets of opaque material within said casing, a plurality of rockerarms equal in number to said switch pairs, each of said rocker armscomprising ends of transparent material integrally joined to anintermediate section of opaque material, a single rod passing throughsaid rocker arms at a point equidistant between the plungers of saidswitch pairs, the plungers 5 of said switch pairs being urged intoresilient contact engagement with respective ends of said rocker armsirrespective of the positions assumed by the same, said casing havingapertures therein which permit each of said rocker arms to protrude fromsaid casing thereby allowing each of said rocker arms to be manuallyrotated in either direction about said rod in order to depress either ofsaid plungers in any one of said switch pairs, a depressed plunger beingretained in this condition by the resilient force exerted against theopposite end of the rotated rocker arm by the other plunger of theswitch References Cited in the file of this patent UNITED STATES PATENTS2,420,066 Conway May 6, 1947 2,860,212 Stearn Nov. 11, 1958 2,870,299Cox Jan. 20, 1959 2,941,047 Grashofl June 14, 1960

